(a) Technical Field
The present invention relates to a safety apparatus of a battery module for a vehicle, and more particularly, to a technology associated with a safety apparatus of a battery module for a vehicle that can maintain stability by opening a circuit to prevent electricity from flowing when a battery cell is expanded by abnormal phenomena (e.g., overcharge, over-discharge, internal short-circuit, substantially high temperature, and the like).
(b) Background Art
A hybrid electric vehicle, a fuel battery vehicle, and an electric vehicle are configured to drive a vehicle by using an electric motor and require a high-voltage battery pack that provides driving power to the electric motor.
The high-voltage battery pack uses a lithium ion rechargeable battery which is considered a next-generation energy storage and generally the lithium ion rechargeable battery type for the vehicle includes varies according to manufacturer, but generally a can type and a pouch type are used, and includes a module and a packet based on the number and shapes of cells which are determined by each manufacturer.
For example, eight battery cells are connected in series to constitute one battery module (e.g., CMA, cell module assemble), and nine battery modules (CMA), one battery management system (BMS), and one power relay assembly (PRA) are combined to constitute one battery pack (BMA, battery module assemble).
A technology that maintains durability and safety is applied to the lithium ion rechargeable battery and a safety device that induces electric short-circuit when an abnormal phenomenon occurs is used to maintain vehicle safety. In other words, parts used as safety elements in the related art include a positive temperature coefficient (PTC), a thermal fuse, a bi-metal with PTC, and the like, and the PTC is an element that has resistance that increases when a temperature increases. The resistance of the PTC also increases under an operating temperature to decrease charge/discharge efficiency and when high current is conducted, voltage drop causes reduction of battery utility zone and further, when the PTC is exposed to moisture, high temperature, and the like, reliability deteriorates. Therefore, the PTC may be unsuitable for a vehicle which is used for 10 years or more.
In addition, the thermal fuse is an element wherein an internal circuit is fused by heat when the temperature of the thermal fuse increases. The thermal fuse has a lower resistance than the PTC and has an increased operating capability when the high current is generated due to short circuit, and the like, but may be fused by heat generated in the cell when overcharged with low current. However, the temperature does not increase up to a fuse temperature due to limitations such as an installation position, and the like and when an element operating at a low temperature is used, the operating capability may decreased due to high current generated at the acceleration of the vehicle, and as a result, the thermal fuse may be unsuitable for being used for the vehicle.
Further, the bi-metal with PTC has a higher resistance than that of a general PTC, but the bi-metal with PTC is unsuitable to be used for the vehicle due to malfunctions of bi-metal by vibration and shock.
The description provided above as a related art of the present invention is just for helping understanding the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.